DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2021-1074; Project Identifier MCAI-2021-00447-R;
Amendment 39-22195; AD 2022-20-11]
RIN 2120-AA64
Airworthiness Directives; Bell Textron Canada Limited Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: The FAA is adopting a new airworthiness directive (AD)
for
certain Bell Textron Canada Limited Model 429 helicopters. This AD was
prompted by reports of failed rivets between the tailboom skin and the
tail rotor (TR) gearbox support assembly. This AD requires visually
inspecting the external surface of the TR gearbox support assembly,
borescope inspecting or visually inspecting the inside of the tailboom
for certain conditions, and performing a tactile inspection. Depending
on the results of the inspections, this AD requires removing certain
rivets from service or repairing gaps in accordance with an approved
method. This AD also requires repeating these inspections within
certain intervals. The FAA is issuing this AD to address the unsafe
condition on these products.
DATES: This AD is effective November 28, 2022.
The Director of the Federal Register approved the incorporation by
reference of a certain document listed in this AD as of November 28,
2022.
ADDRESSES: For service information identified in this final rule,
contact Bell Textron Canada Limited, 12,800 Rue de l'Avenir, Mirabel,
Quebec J7J 1R4, Canada; telephone 1-450-437-2862 or 1-800-363-8023; fax
1-450-433-0272; email productsupport@bellflight.com; or at
bellflight.com/support/contact-support. You may view the referenced
service information at the FAA, Office of the Regional Counsel,
Southwest Region, 10101 Hillwood Pkwy., Room 6N-321, Fort Worth, TX
76177. For information on the availability of this material at the FAA,
call (817) 222-5110. Service information that is incorporated by
reference is also available at regulations.gov by searching for and
locating Docket No. FAA-2021-1074.
Examining the AD Docket
You may examine the AD docket at regulations.gov by searching for
and locating Docket No. FAA-2021-1074; or in person at Docket
Operations between 9 a.m. and 5 p.m., Monday through Friday, except
Federal holidays. The AD docket contains this final rule, the Transport
Canada AD, any comments received, and other information. The street
address for Docket Operations is U.S. Department of Transportation,
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200
New Jersey Avenue SE, Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT: Andrea Jimenez, Aerospace Engineer,
COS Program Management Section, Operational Safety Branch, Compliance
&
Airworthiness Division, FAA, 1600 Stewart Ave., Suite 410, Westbury, NY
11590; telephone (516) 228-7330; email andrea.jimenez@faa.gov.
SUPPLEMENTARY INFORMATION:
Background
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to Bell Textron Canada
Limited Model 429 helicopters, serial numbers (S/N) 57001 and
subsequent. The NPRM published in the Federal Register on December 23,
2021 (86 FR 72891). In the NPRM, the FAA proposed to require visually
inspecting the external surface of the TR gearbox support assembly,
borescope inspecting or visually inspecting the inside of the tailboom
for certain conditions, and performing a tactile inspection. Depending
on the results of the inspections, the NPRM proposed to require
removing certain rivets from service or repairing gaps in accordance
with FAA-approved methods. The NPRM also proposed to require repeating
these inspections within certain intervals.
The NPRM was prompted by Transport Canada AD CF-2021-15, dated
April 14, 2021 (Transport Canada AD CF-2021-15), issued by Transport
Canada, which is the aviation authority for Canada, to correct an
unsafe condition for Bell Textron Canada Limited Model 429 helicopters,
S/N 57001 and subsequent. Transport Canada advises of multiple in-
service reports of failed rivets at the joint between the tailboom skin
and the TR gearbox support assembly part number (P/N) 429-034-701-101
or P/N 429-035-705-101. Transport Canada states that in-service reports
also revealed a quality escape resulted in a gapping condition between
the tailboom skin and the TR gearbox support fitting at some locations
around the joint, and that rivets of inadequate grip length have been
installed at the affected joint. This condition, if not addressed,
could result in progressive deterioration of the joint structural
integrity, detachment of the TR gearbox support assembly and loss of
control of the helicopter.
Accordingly, Transport Canada AD CF-2021-15 requires, for certain
serial-numbered helicopters, an initial visual inspection of the rivets
at the TR gearbox support assembly for signs of failed rivets or
inadequate grip length. Transport Canada AD CF-2021-15 also requires,
for all serial-numbered helicopters defined in the applicability,
repeating the initial visual inspection at intervals not to exceed 400
hours air time or 12 months, whichever occurs first. Transport Canada
AD CF-2021-15 also requires repair or replacement of affected parts if
discrepancies are found. Transport Canada considers its AD an interim
action and states that further AD action may follow.
After the FAA issued the NPRM, the FAA issued a supplemental notice
of proposed rulemaking (SNPRM) to amend 14 CFR part 39 by adding an AD
that would apply to Bell Textron Canada Limited Model 429 helicopters,
S/N 57001 and subsequent. The SNPRM published in the Federal Register
on April 22, 2022 (87 FR 24077). The SNPRM proposed to require visually
inspecting the external surface of the TR gearbox support assembly,
borescope inspecting or visually inspecting the inside of the tailboom
for certain conditions, and performing a tactile inspection. Depending
on the results of the inspections, the SNPRM proposed to require
removing certain rivets from service or repairing gaps in accordance
with FAA-approved methods. The SNPRM also proposed to require repeating
these inspections within certain intervals.
The SNPRM was prompted by the FAA's determination that due to
thermal cycling, the compliance times in the NPRM should be revised to
include calendar compliance times. According to Bell, thermal cycling
is independent of flight hours (FH) and can occur when an aircraft is
stationary and is also a significant contributor to the unsafe
condition. Accordingly, the FAA determined the proposed paragraph (g)
of the NPRM had to be revised by including calendar compliance times.
Also, after the NPRM was issued, the FAA determined the proposed
paragraph (g)(1)(iii) of the NPRM had to be revised by deleting the
word ``not'' when referring to whether or not a rivet comes out when
pulled with pliers or when pulled by hand. This wording was incorrect
and the correct wording should only state ``does.'' Accordingly, these
changes were included in the SNPRM.
Discussion of Final Airworthiness Directive
Comments
The FAA received one comment from Air Methods. The following
presents the comment received on the SNPRM and the FAA's response.
Request for More Information
The commenter stated Transport Canada AD CF-2021-15 requires
replacing any rivets and repairing any gaps that exceed 0.005 in (0.127
mm) in accordance with an approved Bell structural repair scheme,
whereas the proposed AD would require removing the rivets from service
and repairing gaps in accordance with an FAA-approved method instead.
The commenter stated that Bell does not normally provide FAA-approved
documentation and requested that the FAA clarify whether the FAA is
mandating receiving both a Bell Canada approval document and a separate
8110 from the FAA.
The FAA has revised paragraphs (g)(1)(i)(B) and (g)(1)(ii)(A)(2) of
this final rule from ``repair the gaps in accordance with an FAA-
approved method'' to ``repairing any gaps in accordance with a method
approved by the Manager, General Aviation & Rotorcraft Section,
International Validation Branch, FAA; or Transport Canada; or Bell
Textron Canada Limited's Transport Canada Design Approval Organization
(DAO). If approved by the DAO, the approval must include the DAO-
authorized signature.'' The FAA also revised the Costs of Compliance
section of this final rule to reflect these changes. These revisions
clarify that operators are not limited to a single method of repair in
order for a helicopter to be approved for return to service.
Additional Changes Since the SNPRM was Issued
Since the FAA issued the SNPRM, the FAA has revised paragraphs
(g)(1)(i)(A) and (B) of this final rule by adding the words ``replace
the rivets removed from service by paragraph (g)(1)(i) of this AD with
airworthy rivets.'' The FAA determined this revision clarifies which
rivets should be replaced and that an airworthy rivet must be installed
when these rivets are removed from service.
The FAA has also revised paragraphs (g)(1)(i) and (g)(1)(ii)(A) and
(B) of this final rule by adding the words ``remove these rivets from
service.'' The FAA determined this revision clarifies which rivets
should be removed from service. Additionally, the FAA revised this
final rule by adding paragraphs (g)(1)(ii)(A)(1) and (2) to this final
rule, which describe the corrective actions that are required as a
result of paragraph (g)(1)(ii)(A). The FAA determined this revision was
necessary to clarify which rivets should be removed from service and
replaced after the gap measurements.
The FAA has also revised paragraph (g)(1)(ii)(B) of this final rule
by adding the words ``replace them with airworthy rivets.'' The FAA
determined this revision clarifies that an airworthy rivet must be
installed to replace the rivet(s) that were removed from service.
Additionally, the FAA revised the corrective action for any gaps
that equal 0.005 in (0.127 mm). In the SNPRM, the FAA proposed
repairing those gaps in accordance with an FAA-approved method and
removing the rivets from service. In this final rule, the FAA requires
removing certain rivets from service and replacing them with airworthy
rivets for that condition instead.
Finally, the FAA revised paragraph (g)(1)(iii) of this final rule
by adding the words ``remove any rivet from service that comes out when
pulled with pliers or when pulled by hand and replace with an airworthy
rivet.'' The FAA determined this revision was necessary to clarify
which rivets should be removed from service if corrective action is
needed as a result of the tactile inspection and that an airworthy
rivet must be installed to replace the rivet that was removed from
service.
Conclusion
These helicopters have been approved by the aviation authority of
Canada and are approved for operation in the United States. Pursuant to
the FAA's bilateral agreement with Canada, Transport Canada, its technical
representative, has notified the FAA of the unsafe condition described
in its AD.
The FAA reviewed the relevant data, considered the comment received, and
determined that air safety requires adopting this AD as proposed.
Accordingly, the FAA is issuing this AD to address the unsafe condition
on these helicopters. Except for minor editorial changes and any other
changes described previously, this AD is adopted as proposed in the
SNPRM.
Related Service Information Under 1 CFR Part 51
The FAA reviewed Bell Alert Service Bulletin (ASB) 429-19-47,
Revision B, dated January 27, 2021. This service information specifies
procedures for an initial and repetitive general visual inspections and
detailed inspections of the affected rivets at the joint between the
tailboom skin and the TR gearbox support assembly. This service
information also specifies procedures for replacing the affected rivets
and repairing the gaps in accordance with an approved Bell structural
repair scheme.
This service information is reasonably available because the
interested parties have access to it through their normal course of
business or by the means identified in the ADDRESSES section.
Other Related Service Information
The FAA also reviewed Bell ASB 429-19-47, dated August 28, 2019
(ASB 429-19-47), and Bell ASB 429-19-47, Revision A, dated November 2,
2020 (ASB 429-19-47 Rev A). ASB 429-19-47 specifies the same general
visual inspection as ASB 429-19-47 Rev A however, ASB 429-19-47 Rev A
introduces a repetitive inspection and specifies corrective actions if
any discrepant rivets are found. ASB 429-19-47 Rev A specifies the same
procedures for the initial and repetitive general visual inspections
and detailed inspections as ASB 429-19-47 Rev B however, ASB 429-19-47
Rev B revises the compliance section, description section, and
materials section, and also the accomplishment instructions.
Interim Action
The FAA considers this AD to be an interim action. Once final
action has been identified, the FAA might consider further rulemaking.
Differences Between This AD and the Transport Canada AD
If there are any gaps that exceed 0.005 in (0.127 mm), Transport
Canada AD CF-2021-15 requires replacing the rivets, repairing the gaps
in accordance with an approved Bell structural repair scheme, and
submitting certain information to the manufacturer. Whereas, if there
are any gaps that exceed 0.005 in (0.127 mm), this AD requires removing
the rivets from service and replacing the rivets with airworthy rivets.
This AD also requires repairing those gaps in accordance with a method
approved by the Manager, General Aviation & Rotorcraft Section,
International Validation Branch, FAA; or Transport Canada; or Bell
Textron Canada Limited's Transport Canada DAO instead. If there are any
gaps that are 0.005 in (0.127 mm) or less, Transport Canada AD CF-2021-
15 requires replacing the rivets, whereas this AD requires removing the
rivets from service and replacing them with airworthy rivets.
Costs of Compliance
The FAA estimates that this AD affects 120 helicopters of U.S.
Registry. Labor rates are estimated at $85 per work-hour. Based on
these numbers, the FAA estimates the following costs to comply with
this AD.
Visually inspecting the surface of the TR gearbox support assembly
takes about 0.5 work-hour for an estimated cost of $43 per helicopter
per inspection and $5,160 for the U.S. fleet per inspection.
If required, replacing an affected rivet takes about 1 work-hour
and parts cost about $110 per rivet for an estimated cost of $195 per
rivet replacement.
If required, measuring gaps takes about 0.5 work-hour for an
estimated cost of $43 per helicopter.
If required, repairing a gap in accordance with an FAA-approved
method takes up to about 1 work-hour for an estimated cost of up to $85
per repair. The FAA has no way to determine the cost estimate of
repairing a gap using a method approved by Transport Canada, or Bell
Textron Canada Limited's Transport Canada DAO.
Visually inspecting or borescope inspecting the inside of the
tailboom takes about 0.5 work-hour for an estimated cost of $43 per
helicopter per inspection and $5,160 for the U.S. fleet per inspection.
Performing a tactile inspection takes about 0.5 work-hour for an
estimated cost of $43 per helicopter per inspection and $5,160 for the
U.S. fleet per inspection.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs,
describes in more detail the scope of the Agency's authority.
The FAA is issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: General requirements.
Under that section, Congress charges the FAA with promoting safe flight
of civil aircraft in air commerce by prescribing regulations for
practices, methods, and procedures the Administrator finds necessary
for safety in air commerce. This regulation is within the scope of that
authority because it addresses an unsafe condition that is likely to
exist or develop on products identified in this rulemaking action.
Regulatory Findings
This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect on the States,
on the relationship between the national government and the States, or
on the distribution of power and responsibilities among the various
levels of government.
For the reasons discussed above, I certify that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska, and
(3) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
The Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive:
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